This invention relates to a filter element for a rotatable disc filter, and more particularly a filter element which is especially suitable for use with a centrifugal filter.
Conventional filter elements in rotatable disc filters are superposed over each other on a hollow shaft. The shaft and its filter elements are then installed inside a filtering tank or housing.
It has been proposed to provide a filter element for a rotatable disc filter which consists of a conically buckled plate. A filter cloth is stretched over the plate so that the filtrate can flow within the space between the filter cloth and the buckled plate and then can drain off by way of the hollow shaft with which this space communicates
A screen for supporting the filter cloth is commonly found on one side of such filter elements. One of the advantages of the above-mentioned proposed filter elements is that the buckled design of the filter plate makes a supporting screen unnecessary. However, since the plate is of metal this filter element has the disadvantage that it can be corroded by metalcorrosive substances in the material being filtered.
A synthetic resin filter element is disclosed by Swiss Pat. No. 458,286. This filter element is produced from a pressed glass fiber-reinforced synthetic resin plate. However, the synthetic resin element is unstable in the presence of strong mineral acids. This element has adequate mechanical stability despite being made of synthetic material, because it is provided with profiling which defines ring channels but this remedy sharply retards the rate of filtrate discharge. An additional disadvantage characteristic of synthetic resin filter elements is the expense of providing and installing a filtering ring at the center of the synthetic resin plate.